We present a new concept in solar concentrator: spectral splitting. It implies reflective, refractive and diffractive elements that allow two spectrally differentiated beams to reach different and/or ... [more ▼]

We present a new concept in solar concentrator: spectral splitting. It implies reflective, refractive and diffractive elements that allow two spectrally differentiated beams to reach different and/or unmatched lattice solar cells. Those cells efficiencies are then enhanced. The aimed geometrical concentration factor is 5× and the theoretical optical efficiency of that concentrator concept reaches 82%. [less ▲]

We evaluated AJP (Aerosol Jet Printing) deposited silver layer on variety of organic substrates for the most common interconnect techniques for electronic packaging. Specifically, we checked if the AJP ... [more ▼]

We evaluated AJP (Aerosol Jet Printing) deposited silver layer on variety of organic substrates for the most common interconnect techniques for electronic packaging. Specifically, we checked if the AJP silver layer can be electrically interconnected by Au and Al wires bonding technique. We also evaluated suitability of AJP silver layer for surface-mount technology (SMT). We performed electrical characterization of the AJP silver layer. [less ▲]

An object of the present invention is to provide a cheap, rapid, controlled, reproducible and polyvalent method for manufacturing a light emitting device with an internal source of light capable of ... [more ▼]

An object of the present invention is to provide a cheap, rapid, controlled, reproducible and polyvalent method for manufacturing a light emitting device with an internal source of light capable of achieving an enhancement in extraction efficiency. The invention proposes a method for manufacturing an optical layer for a light emitting device having an internal source of light and an optical layer separating the internal source of light and an external medium of light diffusion, wherein the method comprises the use of coherent electromagnetic radiation speckle lithography, such as laser speckle lithography, to make a nano/micro texturation on at least one surface of the optical layer [less ▲]

Direct detection and characterization of faint sources around bright astrophysical objects is very difficult due to the large flux ratio between them. For example, an Earth-like exoplanet is typically ... [more ▼]

Direct detection and characterization of faint sources around bright astrophysical objects is very difficult due to the large flux ratio between them. For example, an Earth-like exoplanet is typically about 1010 times fainter than its host star in the visible spectrum, reducing to about 107 in the thermal infrared. Infrared nulling interferometry proposed by Bracewell, in 1978, appears to be one of the most promising techniques to achieve the high angular resolution and high dynamic range required to allow the ambitious detection of the first exobiological tracers on extrasolar Earth-like planets, if they exist. The nulling interferometry technique consists in adjusting the phases of the beams coming from various telescopes (two in the most simple configuration) to produce a fully destructive interference on the optical axis. The quality of the destructive interference or the so-called null depth (N) relies on the optical component ability to induce a very precise phase shift (e.g. π radians for a two-telescope configuration) and a very low amplitude mismatch over the considered wavelength range. Unfortunately, searching for biomarkers in exoplanet atmospheres requires spectroscopic characterization over large spectral bands. For example, the Darwin infrared space interferometer considered by ESA will operate in a wavelength band between 6 and 18 μm, seeking biosignatures like the O3-H2O-CO2 triplet. The huge flux ratio between the parent star and the planet therefore requires unprecedented highperformance broadband achromatic phase shifters (APS). The performance requirement for the APS components directly comes from the 10-7 planet-star contrast but also from the system architecture and the associate amount of residual stellar leakage. [less ▲]

We propose a new family of achromatic phase shifters that uses the modulated total internal reflection (TIR) phenomenon. These components can be seen as enhanced Fresnel rhombs for infrared applications ... [more ▼]

We propose a new family of achromatic phase shifters that uses the modulated total internal reflection (TIR) phenomenon. These components can be seen as enhanced Fresnel rhombs for infrared applications like nulling interferometry and polarimetry. The TIR phenomenon comes with a differential phase shift between the polarization components of the incident light. Modulating the index transition at the TIR interface allows compensating for the intrinsic material dispersion in order to make the subsequent phase shift achromatic over broad bands. The modulation can be induced by a thin film of a well-chosen medium or a subwavelength grating whose parameters are specially optimized. We present results from theoretical simulations together with preliminary fabrication outcomes. [less ▲]

Thermal infrared (IR) lenses require efficient anti-reflection coating. Moth-eye (or egg-box) 2D subwavelength gratings have demonstrated their ability to reach a very high transmission for a wide wavelength and angular range. The use in thermal IR is simplified by the lower resolution for lithographic technology, compared to visible waveband. However, deeper structures must be engraved and lithography must be adapted to IR materials. In order to be cost-effective, the patterning must be produced by replication techniques, such as embossing. Our laboratory is now experimenting hot embossing of moth-eye patterns in chalcogenide substrates. In this paper, theoretical analysis, micro-lithographic technology and manufacturing processes are detailed. [less ▲]

Nulling interferometry constitutes a very promising technique in observational astrophysics. This method consists in attenuating the signal of a bright astrophysical object in order to detect much fainter ... [more ▼]

Nulling interferometry constitutes a very promising technique in observational astrophysics. This method consists in attenuating the signal of a bright astrophysical object in order to detect much fainter nearby features, e.g. exoplanets around their host star. An on-axis destructive interference is created by adjusting the phases of the beams coming from various telescopes. The huge flux ratio between the parent star and the planet (106 in the thermal infrared) requires unprecedented high performance broadband phase shifters. We present a new design for these key components called Achromatic Phase Shifters (APS). We propose to use subwavelength diffractive optical elements under total internal reflection (TIR) incidence. Our component can be seen as an evolution of the Fresnel Rhomb technology. [less ▲]

This document reports the investigation of the IR materials. The aim is to evaluate their potential in reducing the fabrication costs while ensuring good optical and mechanical performances in the domain ... [more ▼]

This document reports the investigation of the IR materials. The aim is to evaluate their potential in reducing the fabrication costs while ensuring good optical and mechanical performances in the domain of interest. Suitability for space applications will be reported. [less ▲]